Light bars or emergency lights of the type used on emergency vehicles such as fire trucks, police cars, and ambulances, utilize warning signal lights to produce a variety of light signals. These light signals involve the use of various colors and patterns. Generally, these warning signal lights consist of revolving and oscillating lamps having reflective back support members and colored filters as depicted in U.S. Pat. No. 5,091,828.
Many problems exist with the known methods for producing warning light signals. One particular problem with known light bars is their reliance on mechanical components to revolve or oscillate the lamps to produce the desired light signal. Additionally, these components increase the size of the light bar or emergency lights which adversely affect its drag characteristics. Moreover, there is an increased likelihood that a breakdown will occur requiring the repair or replacement of the defective component.
The most common light sources being used in light bars or emergency lights include halogen lamps or gaseous discharge xenon lamps. These lamps emanate large amounts of heat which is difficult to dissipate from the sealed light bar or emergency light and may damage the electronic circuitry contained therein. In addition, these lamps consume large amounts of current requiring a large power supply or large battery or electrical source. These lamps also generate substantial electromagnetic emissions which may interfere with radio communications. Finally, these lamps, which are not rugged, have relatively short life spans necessitating frequent replacement.
Another problem with the known warning signal lights is their use of filters to produce the desired color. This filtering technique produces more heat that must be dissipated. Moreover, changing the color of a light source requires the physical removal of the filter from the light bar or emergency light and the insertion of a new filter. Furthermore, filters fade or flake making them unable to consistently produce the desired color.
These problems associated with traditional signaling lamps are exacerbated by the fact that creating multiple light signals requires multiple signaling lamps. Further, there is little flexibility in modifying the light signal created by a lamp. For example, changing a stationary lamp into one that rotates or oscillates would require a substantial modification to the light bar which may not be possible.
In view of the above, there is a need for a warning signal light that: (1) is capable of producing multiple light signals; (2) producing the appearance of a revolving or oscillating light signal without relying upon mechanical components; (3) generates little heat; (4) uses substantially less electric current; (5) produces significantly lessor amounts of electromagnetic emissions; (6) is rugged and has a long life span; and (7) produces a truer light output color without the use of filters.